This is it, last day of the admission season. But I think it is going to be a thriller.

I have been accepted to one school, and waiting another schoolbecause I am on their waitlist. Until when is it safe to wait? Iam severallhours ahead from USA timezone, but am I safe until the USA time changes?

The resolution does not specify anything about timezone. My assumption would be that you should utilize the school's timezone. It is the hub of decision making. However, it would be prudent to be in contact with the graduate director, so he/she knows not to give away your slot towards the end of the business hours.